+1 for this feature request.
I needed this feature when a certain node started to overlap the arrow. I don’t want to move the nodes themselves to make the arrow visible - what matters to me is the existing arrangement of the nodes and the order on the canvas as a whole. Just as I don’t want to attach the arrow to the other side of the node, because that would affect the meaning of the arrow.
What does this situation look like on my canvas (arrowheads (as well as arrow text) are overlapped by nodes):
Another feature request that is relevant to me in this situation: Canvas element arrangement: bring-to-front, send-to-back